The Chase Bliss EXP Pedal...

At the low end of the guitar pedal marketplace, you have budget pedals: small, very affordable, and all very similar: fuzz, overdrive, chorus, phaser, flanger, delay, reverb...

At the opposite end of the market there are what are often called the 'boutique' pedal manufacturers: sophisticated, beautifully engineered and as some marketing people like to say: 'reassuringly expensive' - but most importantly: diverse and unusual. You won't find conventional 'me too' phasers, loopers or delays here. Instead you will get informed, flexible, powerful, eclectic pedals - plus many other words associated with innovation and exclusivity.

EXP

A perfect example of this (and actually, pretty much a perfect pedal) is the recently announced EXP pedal from Chase Bliss Audio. Wikipedia describe Chase Bliss Audio as being 'high-end', whilst Anderton's Music Company says: '...not just another pedal company, no...21st Century Trail-blazers...'. Chase Bliss Audio themselves say it very nicely on their web-site: 

Chase Bliss makes pedals that mix digital wizardry with analog goodness to create weird and wonderful sounds.

However, the EXP pedal is slightly different - it is just 'analogue goodness'. (No digital inside at all!)

In these days of 'Do you want a microprocessor with that?' turning up in everything, then this is a bold move, but it is a great move.

The reason why this is such an amazing move is that EXP is the expression pedal, reinvented. 

I will let you think about that for a moment...

Instead of an angled foot plate that you move with your foot to control guitar pedals via the 'Expression' input, the EXP pedal looks more like a very robust, very engineered modulation wheel that has escaped from a synthesizer - maybe someone like Expressive E. So you can use it on top of a studio desk, where it gives a nice, convenient, tactile interface to controlling guitar pedals being used as outboard effects, and the classy black metal case with its minimalistic labelling, plus the 'executive toy' knurled texture on the wheel, plus the glossy numbers wrapped around it, mean that it looks like it belongs there. Alternatively, put it on the floor or on a pedal board, and the rugged metal box, plus the grippy metal wheel that can be moved with your foot, mean that it is right at home there as well. 

And whilst you are visualising your foot moving the wheel on the EXP pedal, here's an interesting practical thought: have you ever knocked an expression pedal whilst feeling about with your foot for a foot-switch on a pedal board? Well, the wheel on the EXP is almost immune to such accidents, because unless you put your foot on it and move your foot forwards deliberately, then it isn't going to get accidentally moved... The reason that you may feel the world wobbling a little at the moment is a large number of guitarists all nodding (with a slightly embarrassed smile on their face at various live 'incidents'), plus more nodding of heads from all the live mix engineers who have had to suddenly pull back the sliders for the guitarist who just jumped up 20 dB in the mix.  

So let's look at this design. Instead of 15 to 30 degrees of angular movement from your foot, you have something like 270 degrees of rotation of a wheel, or about 150mm (6 inches) of linear movement of a foot (or hand). So that's lots of fine control, plus there's a big number that shows from 0-10, so you know where you are in the range. I can't recall ever seeing a foot pedal marked off in degrees...

Inside

Now, I have never been able to resist opening up gear, and so that's what I did next...

That's a single piece of bent metal that isn't fastened to either the base of the case (as you can see), nor the top part. It is held in place by the base when the case is assembled, and the electrical connections to the top part of the case are made thru a Molex sparse ribbon cable. As you can see, the wheel occupied all of the available vertical space, nearly touching the base - but it doesn't, of course! What you also get hints of here are some bearings (the thick metal casting in the lower left, and of some mechanics in the central fold hole. 

Sharp-eyed readers (viewers, actually) will probably have spotted that there are two 'stereo' jack plugs connected at the back, and these are for the two electrically separate outputs. The two rectangular hole near the top have two switches just below them, and these can reverse the direction of the outputs, so you can have heel and toe the same or both, or both reverse, or heel and toe opposite in two ways. I set the switches to opposite positions, so that I have two outputs that are the inverse of each other. So whatever I control with expression on one pedal, I can control the opposite on another pedal. But as you can see, just by removing 4 bolts and flipping a switch, I can change that at any time. 

I was pretty impressed with the mechanical minimalism here. I was expecting something much lighter and that the switches would be more awkward to get at. I like good surprises.

(What is interesting here is the forced perspective. You might be wondering why the base looks so much smaller than the case.? The clue is the shadows... Yes, the top part of the case is actually much higher up because I had to stand it on a couple of wood blocks because the wheel sticks out of the top of the case. So the top part is much closer to the camera, which is why the shadow for the top part of the case is diffuse, whilst the shadow for the base of the case is so sharp - it is on the blue background, whilst the top part of the case is about 30 mm above it. So now you know! You eye assumes that the two objects are both on the blue background, and so the base must be smaller even though it is the same dimensions!)

Going a bit deeper was interesting. That single piece of bent metal IS the holder for all the mechanics, and it is not fastened to the top of the case at all. There is just the sparse black ribbon cable. So you just lift out the bent metal...

As I said, the wheel has substantial bearings in those solid blocks of metal. The wheel connects to the pot using a toothed rubber drive belt, so no slipping. and the potentiometer is, as expected, a dual gang linear potentiometer, which explains how the two outputs can be electrically separate - one gang is used for each output. It looks as if the circuit board is held in place by the two jack sockets, so, that's a neat solution as well. The diameters of the wheel gear and the potentiometer gear appear to be pretty much the same size, and so the wheel uses the whole 270 degrees of rotation of the potentiometer, which is why you can invert the ranges for the two outputs.

So the mechanical design is very cool. There are no fastenings needed for the main bent metal assembly to hold it in place inside the case, other than the case itself. The four bolts that hold the base of the case in place, also hold the mechanical assembly securely and solidly in place. The metal is bent to form the supports for the bearings and the potentiometer. I just love it. Minimalistic, with no levers, easy disassembly and it looks like servicing (replacing the rubber belt, or the bearings, or the potentiometer) should be very easy and quick. I'm struggling to find anything to criticise here. 

Even if I was very picky and said that dust might get inside through the rectangular hole in the top of the case for the wheel, then just opening up the case and blowing away the dust is probably going to be all that is required. If liquids get inside, then it is all passive components, and the potentiometer is unlikely to cost a fortune to replace. 

Using it

Expression pedals are made to allow you to control things - to make them expressive. So next, I look at using it...

Well, it works. Wonderfully. It's like an expression pedal, except that you don't rock it from heel to toe with your foot, instead you roll from one end to the other, which seems to be about 270 degrees of rotation, and the end stops feel solid and not sloppy, and not particularly padded. Rather like a lot of synthesizer modulation wheels, actually. Perhaps a little stiffer, but it may loosen up as I use it more. But not a problem. My only criticism is that moving rapidly from heel to toe requires a little bit of practice with your hand (or your foot). 

And there's the amazing thing. It feels right either as a desktop hand operated controller for expression, or on the floor as a foot-operated controller for expression. It is quite heavy, so there's no skittering when you stick the rubber feet on the bottom, and the base is smooth and matt black paint, so Velcro is going to hold it well on a pedal board base. 

There isn't very much room, but I'm sure that someone is going to find a way to put a couple of LEDs inside so that the wheel hole lights up...

(I've tried modding one of my ordinary expression pedals so that they have two outputs, and the problem is that you need a pedal that uses the whole 270 degree range of the potentiometer - and the pedal I used didn't do that... My advice is to only try this on a pedal if you are expert in mechanics, which isn't me...)

With the EXP, it is very cool to be able to seamlessly blend from two very different effects, or even to find interesting points in-between the extremes. As with this type of thing, the more you play, the more you will find. So there's plenty of scope for exploration, and as for robustness, then I would have no hesitation using the EXP live or taking it on tour. 

Expression, and Voltages...

Now I could have used a photo of the EXP connected to the 'Expression pedal' input of a guitar effects pedal, and it would be ever so slightly boring and obvious. Instead, here's a photo where the guitar effects pedal is off camera, way to the left, and instead, the EXP is connected to a little bit of hardware (the 'EXP CV' box) that I threw together, because the design of the EXP also makes it well (maybe even uniquely) suited to also being used as a robust CV controller.

Nope. I haven't gone mad. Expression pedals output a voltage, which used to be somewhere from zero Volts-ish to somewhere less than 5 Volts. These days, processors tend to run on just over 3 Volts, and so somewhere in the range of 0-3V-ish is where you expect an expression pedal to output. 

(What happens is that a guitar pedal 'expression socket' does two things: it provides power to an external potentiometer inside the foot pedal, and then it receives the output of that potentiometer back as an input! So older pedals provided 5V power to the external foot pedal, whereas modern pedals only provide 3.3V. The potentiometer just taps off a percentage of the voltage, so if it is half-way round its whole rotation, then it outputs 50% of the voltage, so for 5V that would be 2.5V, and for 3.3V it would be 1.65V. The guitar pedal knows what voltage it outputs, and so it can calculate how far the foot pedal has rotated. This dual-function: providing a voltage output and a 'rotation' input, is why you need to use a 'stereo' cable for expression. So three (3) wires are needed: Ground (common to both functions, the Power (5V, 3.3V...), and the Rotation CV from the potentiometer - and a 'stereo' jack provides three connections. Note that the foot pedal doesn't care about the voltage - the potentiometer only outputs a 'rotation' CV that is proportional to how far it has been rotated. )

The range depends on the mechanical linkages used in the pedals - levers don't always seem to rotate the potentiometer through the full 270 degrees - as I noted earlier. But the EXP pedal does use the whole range, and so you can have two opposite outputs that both go from heel to toe. This is so cool, especially when you've tried to make a pedal like this and failed! 

So the mysterious box that is connected between the distant guitar pedal and the EXP is a new generation of my expression pedal range tester. It is ridiculously simple: two stereo jack sockets connected in parallel, and a 3.5mm mono jack socket for the CV output. 

To this simple circuit I have added a cheap three-wire voltage display module (a voltmeter) from Amazon, plus four AA batteries in a holder to provide power for the display. One of the things that isn't well publicised about voltage displays is that the two wire versions are powered from the voltage you are trying to display, and they typically need at least 4.5 Volts to work. So you can typically measure (and display) voltages from 4.5V to about 30V. When the display goes off, then you know that it is below 4.5V! 

But a three-wire voltage display module has an extra wire (usually white or grey) that connects to the voltage that you want to measure, whilst the usual black (the common ground connection) and red (power) wires go to a separate power supply - in my case, those four AA batteries in a holder. Anyway, the display is thus powered separately from the voltage that is being measured, and in this case, separately from the expression pedal socket of the guitar pedal. The end result is that the batteries give me a 6V power supply for the voltage display, which is fine for measuring the 0-5V (max) that expression pedals normally output. 

Using this voltage display technique to make some measurements, my M-Audio Expression Pedal can output between 0-2.75V to 2.84-3.14V for a 3.3V expression pedal socket, my Bespeco between 0-3.18V, my Nektar between 0-3.07V, and my Casio VP-1 between 1.68-2.56V. I will leave it as a challenge to you to figure out which pedal I tried to put a dual gang potentiometer into... 

The EXP? It produced 0-2.76V for one switch position, and 0-3.04V for the other position. So, for the first time in the review so far, a not-quite perfect result. But bear in mind that this is not a specified parameter for the EXP, or for any other expression pedal that I have ever bought, so I am being way beyond picky here. And when connected to a range of pedals (Empress, EHX,  TC Electronic, and Keeley), the EXP performed exactly as it should. 

One thing to remember when doing this kind of testing is that most guitar pedals seem to detect when an expression pedal is connected to their expression pedal input only when the power is turned on. So you need to power the guitar pedal down, insert the expression pedal (or EXP!) jack into the expression socket, and then power the guitar pedal up. The expression pedal (or EXP) will then be recognised! 

(If you just plug an expression pedal into a guitar pedal without cycling the power, then it may not be recognised at all - as I found out when doing all the unplugging and plugging...)

Anyways, in the photo above, the mysterious box displaying 1.24 Volts in blue digits is showing the output of the EXP when set to about a setting of 5, with the 'source' voltage from the guitar pedal's Expression socket of about 3.3Volts. That 1.24 Volts is what appears on the orange 3.5mm jack plug.

Yep, not a 'converter', more an extractor, or a rerouter, or an 'in another way' box. But yeah, it takes an EXP and outputs a CV. So what can we do with that?

First off, lets check the voltages and how they correspond to the EXP wheel setting:

Okay, so zero on the wheel is zero Volts. Cool.

Aha! So 10 on the wheel is 3.04Volts. Makes sense. So we have 3 Volts of CV range to play with... So 6 and a bit on the wheel would be about 2 Volts?

Yep.

One thing we could do with this is connect the orange 'CV' patch cord into something modular. The Rebel Technology 'Witch' is a good example. It is a programmable synthesizer, processor and effects unit that has CV and Gate inputs and outputs (plus audio I/O), is a USB Audio interface and Host, and does way more than you would expect for such a small box. A tiny modular system in a little box, and huge amounts of fun with elastic/flexible capabilities because you can reprogram what it does from a library of patches (and store eight patches inside the Witch for instant recall with those round buttons!). In this case, the CV input is controlling Input A, which sets the pitch of a drone patch. Now if the other EXP expression output was controlling a pedal using the expression socket, we have even more sound-making capability in a tiny space. Wooh!

Getting a CV output from an EXP is nice, but it isn't a MIDI Controller. or could it be? Here's that control voltage (the red cable) going into the CV input of the amazing Befaco VCMC - a Voltage Controlled MIDI Controller. So the MIDI socket in the top left hand corner of the VCMC is outputting MIDI Continuous Controller messages using a CV extracted from the expression control output from a Chase Bliss EXXP Pedal that is simultaneously controlling a guitar pedal off to the top left. Oh, and 8 on the wheel outputs about 2.64Volts...

Now to use this CV output in a larger modular Eurorack (or other modular), then you would need to scale this voltage to make it slightly larger. So some sort of Utility or Maths module would be the first port of call. After that, then you could use it to control just about anything. For me, having those numbers on the wheel means that I have a repeatability of setting a value that I don't get with foot pedal controllers, and being able to control two guitar pedals (in opposition, if I want) plus having a CV available as well, opens up huge avenues to explore...

Voltmeter displays

I need to point out that low-cost Voltage displays from Amazon are not always very accurate in my limited experience (Some may be - your experience may differ. Other voltage displays are available.). I've compared the values displayed here with my own slightly more expensive multi-meters, and whilst the multimeters are 'reassuringly' similar in the value they display, the voltage display tends to be about 0.3Volts lower. Not perfect, and so there should really be a little sticker on my EXP CV home-brew box that says: 'For Indication Purposes Only. Not Calibrated'. But for indicating what sort of voltage is coming out of the EXP, it works fine. And blue displays just look super cool!

Oh, and the EXP CV box that you see here is my own personal home-brew hand-built utility box. Not connected in any way with Chase Bliss Audio. It is not for sale (I don't do Klon pedals either...). If you happen to make a box anything like it yourself then that (and what you do with it) is entirely your own  responsibility - you do it at your own risk. 

The EXP pedal 

And that about wraps it up for this quick look at the astonishing piece of mechanical engineering that is the Chase Bliss EXP Pedal. There's a lot you can do with it, and it puts 'expression' control of guitar pedals into a rather different place when you go beyond the usual 'foot pedal' user interface. I really like having a 'Mod Wheel' for expression, and I intend to use my EXP a lot! Congratulations to Chase Bliss Audio for a very different approach to controlling expression!

I bought the Chase Bliss Audio EXP pedal with my own money. I am not getting paid by Chase Bliss Audio for this review. But I do think they make very interesting pedals. My kind of pedals! (And hopefully, yours too, now!)

Links

Chase Bliss Audio

Rebel Technology Witch

Befaco VCMC

Expressive E

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Step sequencer for echo delay time...

Now if this was a YouTube channel, then I might well be posting videos with click-bait titles in an ongoing quest for subscribers (or publicising an amazing device like the Rebel Technology 'Witch'!). 

But this is a blog, and I'm happy to post anything I do, that might be useful, which is why there's an eclectic mix of topics on here. And yes, I know that I haven't covered MaxForLive for a while, and there's a very good reason for that. 

Anyway, here's a little bit of fun that might be useful to some of you, or could serve as inspiration for further exploration. I'm almost tempted to post a version on YouTube with a Click-Bait-oriented title just to see what happens... 'Expression Sequencing - What you need to know!' 

Photo by Steve Harvey on Unsplash

Step Sequencing

Okay, I admit, I've been a fan of step sequencers since seeing Tangerine Dream back in the 70s at the Liverpool Empire. Dry ice clouds, mist curtains, mirror balls, CO2 lasers, guitar solos from Edgar Froese and just one or two step sequences - it was quite an experience. Since then, I have acquired a few hardware step sequencers (a Zaquencer, for instance - very nice!), and programmed a few (several in MaxForLive, for example), but my latest acquisition is a little bit different: a mix of old school (8 steps!) and new-ish school (MIDI Clock sync!). But not a Eurorack module - nope, this is a 'guitar' pedal. 

Now, I was raised on Electro-Harmonix pedals (I always wanted an Electric Mistress Flanger!) and I've gradually been getting a few modern examples, purely for research purposes, you understand. The 'pedal' in this case is on the borders of the pedal-world - it is the 8 Step Program: a CV/Expression sequencer. 

Sequencers in pedals are quite unusual, or at least, from my limited viewpoint, that seems to be the case. The Strymon 'Night Sky' has a sequencer to ty and liven up the shimmer reverb, is one example, and I'm not immediately familiar with any other examples. Of course, with thousands of pedal manufacturers and hundreds of pedals released every month (week? day? hour? minute?), then there could well be many other examples, but I'm beginning to think that it is not humanly possible to keep up with pedal releases any longer. Although, if anyone can, it would be Josh Scott of JHS Pedals...

Actually, the step sequencer that I'm talking about is quite unusual, even in a world where unusual and rare seems to be the starting point for a product, and you probably need endorsements by several online influencers just to rise above the lowest levels of noise and avoid being totally ignored. Electro-Harmonix do not shy away from making radically 'different' pedals, and they have a huge range, plus a long and fascinating history. 

Anyway, the '8 Step Program' is s step sequencer for Expression Pedal control signals.

My EHX 8-Step Program pedal!

You read that correctly. Whilst it can also output control voltages (from 0 (zero Volts) to 5Volts), it is mostly intended to act as an automatic Expression Pedal, so instead of you having to move your foot from heel to toe on an Expression Pedal, then the 8 Step Program will do it for you, repeatedly if you prefer, at a user-variable rate, or you can advance through the steps manually, or just trigger a One-shot single run-through. At the borders of 'step sequencing', there is also the ability to select steps at random, which always sounds more like a slow random noise generator to me, although it outputs a very structured type of noise where the levels are known, but when they will occur is not known.  I'm going to step away from this topic before any 'unknown unknowns' are mentioned!

Oh, before I forget, sincere thanks to Andertons for managing to procure me an '8 Step Program' on special order. It is definitely worth the wait!

Ubiquity or Not

Lots of guitar pedals have a socket marked 'Exp' or 'Expr'. Not all pedals have them, and for those that do, there are at least two different ways to wire the socket (and the pedals) in common usage (see this blog post...). So not quite ubiquitous, but certainly widely available. As that previous blog post rather gives away, I'm one of those people who likes to use a foot pedal to change one or more parameters on a pedal, and so I have 'one or two' Expression Pedals'. 

I've always been confused by the naming convention for guitar pedals, and that ignores the weirdness that you can use them with things other than guitars! One of the first pedals I ever bought was a Colorsound Wah-wah pedal (Not this modern re-creation and not from Macari's, but way older and from somewhere else, lost in the fog of time...) and this was indeed, a pedal. There was a bit that you put your foot on and moved it, and it changed the sound, and it looked like a sort of hi-tech equivalent of the pedal that my Mum used to control her sewing machine. So my mind is forever locked into the mind-set that a pedal is a thing that you move (heel and toe positions, plus in-between) with your foot. A foot-pedal. A Guitar foot-pedal. 

But then there was another type of guitar pedal, and it didn't have a wobbly bit on top where you put your foot. Instead it had one (and sometimes more!) push switch that made a metallic snicking sound when you pushed it - and this turned the effect on or off. Bypass was the word - on or off. To change the effect, you turned small rotary controls - too small and awkwardly placed for your foot, of course. Most of the foot-switches were chrome cathedrals of mechanical complexity, but there were also ones with black plastic tops that didn't have the same satisfying metallic clunk, and which were apparently notorious for 'going wrong'. Nowadays, I only ever see the all-metal variety of foot switch, so I imagine that the plastic-top ones have died out. 

When there are two things that are different but share the same name, then confusion is not far away. As I said earlier, I've always been confused by guitar pedals: some of which have a foot pedal, and some of which don't, but they are still called pedals. Expression Pedals, which don't process audio at all, and only control other guitar pedals, via a TRS or 'stereo' cable, are a third type of pedal again. Your task, should you choose to accept it, is to try and persuade me that there are three types of totally different device, all called the same, where:

- one device processes audio

- one device processes audio, and has a pedal that your foot moves

- one device does not process audio at all, but controls a device that does process audio.

 And these are all Pedals?

Sequencing...

Let's look at what you can use Expression for. That Colorsound Wah-Wah pedal is a good starting point. The foot pedal bit changes the audio that passes through the Wah-Wah pedal - it's a band-pass filter where the centre frequency of the filter is controlled by the foot pedal that your foot moves. The sound is a rough approximation to the band-pass filter that your mouth makes when you open and close it. Try saying 'wah wah wah...' and see how your jaw moves, your mouth opens and your lips move. If you say 'Waaaooouuuw' then your mouth, lips and jaw will all be moving a lot! 

Take a moment here to let the skin on your face return to normal after all that stretching...

Auto-Wah removes the foot pedal and replaces it with an LFO - a Low Frequency Oscillator. A circuit that wobbles something - in this case, the wah-wah effect. So the centre frequency of that band-pass filter wobbles up and down in frequency, and you don't wear out your foot or ankle by moving the pedal back and forth all the time. So the foot pedal bit has gone, and we have just a 'Bypass' switch to turn the effect on or off. 

Of course, some Auto-wah pedals have Expression inputs, and if you connect an Expression Pedal into that input, then you have a foot pedal that controls another pedal!  So if you don't want repeated Wah-Wahs at the rate set by the LFO, then you can use the Expression (foot) pedal to do the 'wah'ing yourself, at whatever rate you want. 

The 8 Step is like an Expression pedal, except that it doesn't have a foot pedal bit that you move with your foot: instead it has 8 linear slider controls that are activated in turn by an LFO. So you get up to 8 different settings of a non-existent foot pedal, sent down a TRS 'stereo' cable, to another pedal where those settings affect the audio. 

If you really want to blow your mind, then the 8 Step Program also has an input for... an Expression Pedal!

Wah, not wah...

I haven't been using the 8 Step Program to control Wah-wah effects. I've been playing with Echo Units or Delay Lines - audio boxes that apply echo or delay to audio signals. Small cyclical changes to the delay/echo time produce flanging, chorus, tremolo, vibrato and other 'Modulation'-type effects, but sudden jerky changes have a very different effect - they change the rhythm of the echoes. If you change the timing of echoes or delays with a Step Sequencer, then you get a sequence of different rhythmic echoes. It's an interesting and unusual effect - particularly because it doesn't settle down into a fixed rhythm. The echoes are always changing, and if the rate of the Step Sequencer (in the 8 Step Program) is not synchronised to the timing of whatever audio you are processing (a drum machine, or groovebox, or a synth playing a sequence, then the two different rates should drift past each other, and you should get 'skying', where things gradually change in a way that is beguiling, non-repetitive, and addictive.

So, above is the setup. The 'Expression' control signal goes along the TRS 'stereo' cable from the 8 Step Program device to the Echo pedal, and inside the Echo pedal, the Expression is mapped to control the delay time. The 8 Step Program's 8 numbered 'step' sliders are set to a rising stepped 'sawtooth' type of waveform, and the Rate slider on the 8 Step Program is set so that each step is close to one repetition of a drum pattern or a sequenced synth line. 

The results are 8 different patterns of syncopated echoes, because the steps from the 8 Step Program give the equivalent of 8 different settings of the 'virtual expression pedal' that the 8 Step Program is emulating.  Unlike a human being, the 8 Step Program reproduces those 8 steps more or less exactly the same each time, and so it is possible to really hear the 8 different patterns cycling through. Best of all, the Rate slider of the 8 Step Program and the audio clocks are not in sync, and so the patterns gradually change as predicted. 

What I haven't checked out yet is to use a MIDI Clock to do the exact opposite: put the 8 Step Program and the audio into sync. Even when I do, then there is still scope for additional experimentation. The 8 Step Program allows the number of steps in the sequence to be changed, so the length could be set to 7 steps instead of 8. This would mean that even though the 8 Step Program, I mean the '7 Step Program', and the audio drum machine or synth sequencer are in sync, there is a 7:8 ratio of timing, and so they will drift or slip against each other, and so they will generate long repeating patterns that last over many bars. So that is ratios of 1: 8 through to 7:8, plus 8:, which is in sync.

The 8 Step Program also allows the step sequence to run in Reverse (which isn't going to be very different - the patterns will just be different), and in Bounce mode, where the steps go back and forth from 1 to 8 to 1 to 8 etc., scanner-style. Now this 'bouncing' is 15 steps in length, which means that we can have ratios of 9:8 through to 15:8. There's quite a lot to play with here.

There's one final mode for the step sequence., and that is Random, where the steps are not output in sequence, but at random. So after step 1, then any of steps 1 to 8 could follow. This will again give 8 different syncopated echo patterns, but they won't be in any order, and so there will be less obvious patterning for a human being to detect - plus the patterns will not repeat after the same number of bars each time, because the patterns are selected randomly. Again, there is lots of scope for exploration here.

Other devices... 

I've always liked Echo as an effect, but any pedal with an Expression input socket can be used with the EHX 8 Step Program. So Reverb, Flanging, Phasing, Tremolo, even Wah-wah could all be controlled using the 8 Step Program. And all of this complexity and syncopation is totally DAWless!

The 8 Step output is also a Control Voltage (CV), and so with a 1/4 inch jack to 3.5 mm jack, could be used to control Eurorack modulars. In fact, the Expression Pedal input of the 8 Step Program can be used to control parameters like Rate, Depth, Glide (You can set how quickly the steps go from one to the next - a bit like Portamento on a keyboard..) and Sequence Length, as well as a Clock input, so there are many more interfacing options there with modular synths. 

MIDI-wise the 8 Step Program has full MIDI Control over programs of steps, plus all the parameters.  Future investigation for me...

Summary

The Electro-Harmonix 8 Step Program is just a small pedal, but there are lots of ways of using it in a DAWless setup to do things which will sound complex, syncopated and yet, can have the unpredictability, drifting and all of the unexpected serendipity of analogue modular. Using the 8 Step Program to drift through some syncopation delay effects from a DAW output might also change some opinions about the inherent boring repetition that you get with a DAW. I'm wondering if there is scope for a contest where people compete to fool a panel of judges with their DAWless or DAW systems... Now that sounds like an interesting event for a synthesizer booth type gathering!

So you can hear how all this sounds, there's a YouTube version of this blog article on... YouTube!  There are only a couple of examples, but I'm sure that you can come up with your own. Just tell EHX or  Andertons that I sent you when you get your own 8 Step Program!

The EHX page for the 8 Step Program lets you download the manual, which is full of loads of details about what it can do. Please try not to drool onto your screen...

(Note that I bought the EHX 8 Step Program with my own money, from Andertons. This blog post was not sponsored by EHX or Andertons. I just buy stuff from them because I like them!)

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Repairing a Vintage Expression Pedal

I've had my Casio VP-E Volume Pedal (which also works as an Expression pedal) for what is probably well over 30 years. So I wasn't hugely surprised when it started to get a bit noisy. Now it is very robustly constructed, with lots of aluminium extrusion, and it is a classic mechanical foot pedal, so it seems as if it would be a very good candidate for trying to fix - probably by replacing the potentiometer inside.

There are quite a few designs of foot pedal, ranging from simple passive mechanical designs (with levers or gears) through to sophisticated active electro-optical or magnetic circuits. The Casio VP-E wasn't crazily expensive when I bought it (to go with a Casio CT-1000, if memory serves me...), and you can see a white plastic lever when you move the top plate of the pedal, so it looked like it was a straightforward mechanical design.

Opening the VP-E is easy - there are three self-tapping screws that hold the metal end-cheek in place. 

Self-tapping screws into aluminium extrusions was a standard way of making guitar pedals back in the 70s -  I can remember a Carlsbro Flanger pedal built exactly that way from the late 1970s the was built that way. Not exactly an EHX Electric Mistress, but I'm sure it was cheaper... You can see one of the Carlsbro Flange pedals here...  and (closer up) in this eBay advert (over $600!), although it will probably be gone by the time you read this... and here (from an effects database)... It's interesting to see that the Carlsbro pedal is now worth more than the CT-1000, although the Casio was a very early 'almost a synth' from Casio, but only two and a half years before the CZ-101 et al, which were definitely synthesisers! 

So here's the mechanical arrangement. A bent (probably white (natural) nylon) lever, with a pivot underneath the foot plate on the top of the pedal, a second pivot close to the potentiometer, and result is that the potentiometer rotates a lot more than the foot plate. The 15 or so degrees of rotation of the foot plate is converted to something like 130 degrees of the 270 or so in a typical potentiometer. There are designs with gears that can do more, but this design is robust and has lasted decades for me so far. 

It all looked very straight-forward, and so would be easy to fix myself. Remember that I've been doing this stuff for decades, so I have lots of experience. If you aren't sure, then go to an authorised, approved, qualified repairer or service centre and get a quote for what you want doing... Keep safe and carry on!

The short black piece of plastic (at the end of the white lever) is wrapped around the potentiometer shaft and tightened with a grub screw. Loosening this screw allows the lever to be moved out of the way. 

Yep, as suspected, it is just an ordinary (for the 1970s or 80s) potentiometer - and easy to replace. 

Now that it is exposed, the potentiometer nut can then be removed and the potentiometer unsoldered. Note how the wires are connected to it - take a photo with your mobile phone!

It is a 47 kOhm Logarithmic pot (short for 'potentiometer' - can't think why anyone would want to shorten that word!), indicated by the 47K and LogB labelling. European pots of this vintage are usually marked A for linear, and B for log, which is different to the rest of the world, where A often means log, B linear, and C anti-log. 

Linear means that the output of the pot changes as you might expect when the shaft is rotated, so it outputs half when half way round. A logarithmic pot doesn't do this - some things just aren't linear. one example might be a frequency control - human beings hear octaves when a frequency is doubled, so if you had a linear pot, then going from 110m to 220 Hertz would be fine, but the next octave up is 440 Hertz (A3 or 4, and that's another story), and the next one is 880 Hertz, and the 1760 Hz. So if we used a linear pot to set frequency, then the low octaves would all be squashed up at one end, and the high octaves would be widely separated at the other end. A log pot would space the octaves out evenly as you rotated it.

Even though the intention is to get a control voltage from our expression pedal, the lever doesn't convert the rotation of the foot plate into rotation of the potentiometer shaft perfectly linearly, and so a log pot is used to give a 'compromise' that feels okay when you use it. Some high-end optical or magnetic expression or volume pedals have a much better relationship between the foot pedal movement and the output, but then they don't have pots inside...

If you feel like becoming a scientist, then you could try plotting the output of the pedal against the foot plate rotation. It ought to be linear-ish. Here's what I found with some of my 'basic' expression pedals:

I should point out here that I don't calibrate my expression pedals, and this is the first time that I've done any comparison process. I'm now wondering if I should do some work on getting them more closely aligned / linearised, although I don't use them interchangeably - they are each usually assigned to a specific role with a particular guitar pedal or synth. I haven't included my Yamaha FC-7 pedals because they are only ever used with my SY99 and Montage. If I was to try and align the pedals detailed here, then that would probably require some custom hardware and software, and that could easily turn into something expensive and time-consuming. I have worked on International Standards (I was one of the Editors of an ISO-MPEG standard...) and I'm not aware of a formal standard for expression pedals - but there are definitely two different ways of using the Tip and Ring connections. As always, my advice would be to use the expression pedal that is recommended by the manufacturer of what you are plugging the expression pedal into. So for my Yamaha synths, then that is the FC-7. 

There are other types of resistance law as well, with various special audio tapers that are found in some amplifiers. If in doubt, then measuring the end-to-end resistance with a multimeter and then plotting the resistance from one end to the wiper, will quickly show if it is linear or logarithmic (or something else!).

There are several different types of potentiometer that are available: ranging from the expensive Cermet track material that has good thermal characteristics, through more modern 'plastic' materials, and finally to the cheap carbon tracks of ordinary 'basic' potentiometers. There are wire wound pots, but these are coarse and noisy, and would not be my first choice for a pedal. 

eBay.co.uk rapidly provided a replacement pot, and this was quickly fitted. Well, I say quickly, but the soldering to the pot was very much 'old school' soldering, maybe from a person used to valve circuitry, because the wires were threaded through the holes in the three terminals tags, then wound around and soldered. This sort of arrangement doesn't fall off, even when all the solder is melted. Pulling at the wire, especially with molten solder present, isn't very good at removing the wire either - and it can spray molten solder everywhere. One effective technique is to cut the wire with cutters, close to the tag, and then to remove the remaining copper wire and use a solder sucker to clean it all up.

(One thing that the InterWeb has revealed to me is that the British pronunciation of 'solder' says the 'L', as in 'sole' 'duh', whereas the US pronunciation drops the 'L', as in 'sodder'.) 

When replacing old pots, then don't forget that pots from the 70s will probably have 1/4 inch shafts (6.35mm), whereas modern pots are more probably going to be 6mm or even smaller in diameter...

Once the old pot was out, the replacement potentiometer shaft was cut to length, was soldered to the cable, was securely fastened in place with the star washer and the nut, and the lever and grub screw were tightened again to grab the pot shaft. Finally the end-cheeks were put back and the pedal tested with the multimeter again. The pot measured 50k as expected (tip to sleeve), and the wiper (ring) to ground (sleeve) varied from 28.9k to 2.2k. Not perfect for a volume pedal, but fine for CV/Expression use... and I could always adjust the angle of the pot shaft if I needed to...

I did contemplate buying a dual-gang pot so that I could have two separate outputs, but decided, based on the astonishing price of the decade-older Carlsbro Flanger pedal, that it would be better to leave it unmodified. 

I now have a slightly smoother and less noisy Volume/Expression pedal!

Theory - Expression Pedals

Expression pedals, and in fact, any foot pedal that provides a Control Voltage that is used to control Expression or Volume in an electronic musical instrument, all tend to have similar designs, particularly at the budget end of the market. Although note that there are at least two different (and incompatible) ways to wire up the stereo jack plug (OK, the balanced jack plug commonly known as a 'stereo' jack), and specifically note that higher-end pedals might well have very different circuits and pin-outs because they use electro-optical or magnetic foot-plate rotation sensing methods. 

Of course, you should always use the Expression pedal recommended by the manufacturer of the guitar pedal or instrument that you will be connecting the expression pedal to... but if there isn't a specific recommendation...

The circuit is very simple. The potentiometer (the fancy word for the electric component that a Roary control or Knob adjusts) has a voltage at one end, and ground at the other. The 'Wiper' then outputs a voltage between the voltage and ground, depending upon how mucho it has been rotated. At one extreme of rotation it will be the voltage, whilst at the other it will be ground. Most volume/expression pedals do not rotate the potentiometer through its full 270-ish degrees of rotation, and so the output never actually reaches the full range from voltage to ground. 

As a side note, this is why many guitar pedals get you to use your Expression pedal when you set up the knobs that are going to be controlled by the expression pedal. By getting you to set the expression pedal to the two extremes (Toe and Heel positions) and then set the knobs where you want them for each extreme, then the guitar pedal knows exactly what the range of control voltages from the expression pedal are...

Some pedals have a switch that swap the ring and tip connections, so that the two main variations are covered. Most of my equipment seems to have the ring as the CV/Wiper connection, the sleeve as the Ground connection, and the Tip as the positive Voltage connection (which can vary from 3.3V (or lower) to 5V, depending on what it is powered from... As always, if you rewire anything, then you do so at your own risk. 

Anyway, the 'swap' circuit uses a DPDT switch (Double Pole, Double Throw) and the circuit looks complex when the two positions are shown (above). The DPDT switch has two 'Either/Or' switches: so One input and Two Output (of which only one can be connected to the Input at any time). But if you think about how you would actually solder the wires to the DPDT switch itself, then the wiring is lots simpler - the input is on one side, the output is in the middle, with a pair of wires crossing over to give the 'swap' function. And that's it. Drawing the circuit out in full kind of makes it look more complex than the actuality.

I didn't add a switch to the Casio VP-E pedal, and I didn't add in the missing series resistor between the potentiometer and the CV point. I decided to keep the pedal 'as supplied'. If I was being technical, then my defence would be that the cable and the plug/socket have some inherent resistance, and so I would just be adding a bit extra.

Modding / Customisation Warning

Of course, you should always use the Expression pedal recommended by the manufacturer of the guitar pedal or instrument that you will be connecting the expression pedal to...  Also, if you modify / change / rewire anything, then you do so at your own risk. If you are not confident of your ability (or your equipment is still covered by a warranty or guarantee) then you should go to an approved, qualified repairer or service centre for any repairs, modifications or customisations. Safe, not sorry, is the correct attitude to have.

*** 8th November 2021 ***

I have added a few minor corrections here and there, and will add a 'voltage output' chart as well in the next couple of days...

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